1: In a large bowl, combine the ground beef, onions, sour cream, eggs, bread crumbs, salt, pepper, allspice, and nutmeg. Mix well.
2: Form the mixture into small meatballs.
3: Heat oil in a large skillet over medium heat. Add the meatballs and cook until browned on all sides.
4: Remove the meatballs and set aside. In the same skillet, add sliced onions and mushrooms, and cook until soft.
5: Sprinkle flour over the vegetables and stir until mixed. Gradually add heavy cream and chicken stock, stirring until the sauce thickens.
6: Return the meatballs to the skillet and simmer in the sauce for a few minutes.
7: Adjust seasoning with salt and pepper, then serve.
